Core binder material



Patented July 19, 1938 UNITED STATES CORE BINDER. MATERIAL Arthur W. Goos, -Marquette, Mich, assignor to Cliffs Dow- Chemical Company, Marquette, Mich., a corporation of Michigan No Drawing. Application July 2, 1937,

Serial No. 151,661

1 Claim. (C1. 22-188.) w

This invention relates to an improved core binder for use in making foundry castings and the like, and to. a material for this purpose derived from the pyroligneous liquor obtained in 5 the destructive distillation and carbonization of wood.

In the destructive distillation or carbonization of wood there are originally volatilized many substances which, when subsequently condensed, are

found to be incapable of revolatilization. Other substances are present which although volatile under some conditions are not volatile in the presence of water. These materials are found in the soluble tars and a portion of the insoluble or settled tars. The expression soluble tars, otherwise called dissolved tars, is

defined here as that portion of thepyroligneous' liquor obtained in the process of wood ,carbonization which remains as a substantially watersoluble residue after substantially all of themsoluble or settled tar has been removed, and after the methanol products, (including acetone, methyl acetate, etc), acids of the acetic acid series, wood oils, and other compounds azeo-' tropic with water, and most of the water have been substantially removed therefrom by distillation and/or evaporation. Depending upon the method employed in its isolation, soluble tar may accompany other tarry residues so that when the mixture is isolated it is only partially'water-soluble. In such cases the water-soluble portion will contain the soluble tar. The expressions soluble and insoluble, employed in connection with the tar fractions, refer to the solubility of these materials in water. I have found that soluble tars can be obtained in a variety of ways depending on the refining processes employed in producing recognized useful products from the pyroligneous liquor. Regardless of the refining 40 method employed these tars are invariably present. It has long been the practice of wood distillers to consider residuescontaining the soluble' tars as waste products and in spite of their low calorific values, these have ordinarily been I burned or otherwise destroyed.

terials. The soluble tars, being inedible products, may readily replace and make available'for employment in food products those edible materials heretofore employed as core'binders. I have found further that the soluble tars derived from any type of wood ordinarily subjected to carbonization may be employed for this purpose regardless of the'methodby which the wood is carbonized or treated. Several processes are employed in the Wood distillation andcarboniza- 10 tion industry which result in the formation of soluble tars which can be isolated by the methods outlined brieflyin the following paragraphs.

The water-soluble portionsof the material precipitated electrostatically, or byany other partial 15 condensation, from the hot vapors from wood carbonization retorts prior to condensation of substantial quantities of water therefrom, contain substantial amounts of soluble tar which is useful as a core bindingiagent. 20

In carrying out the so-called' calcium acetate process, the pyroligneous liquor. may be substantially freed from insoluble tars, suitably by decantation, prior to the evaporation from such liquor of the methanol products and the acid products. Occasionally, however, the insoluble tar, is left in the liquor. The'methanol products, 1. e. methanoLacetone, methyl acetate, etc., may be removed from the'liquor prior to the acid evaporation step or they may be distilled con- 30 currently with the acid portions. In any case: the water-soluble portion of the material remaining ,as;'a.residue, or tar, after the point in the process at which the acids have been removed by distillation or evaporation, is useful 35 as a core binder.

' The pyroligneous liquor from wood carbonization may be separated'from insoluble tar, esterified, and the volatileproducts including methyl acetate removed by distillation. residue contains soluble tar.

Some processes for the'recovery from the pyroligneous liquors of acids of the acetic acid series involve an extraction of such acids from'the pyroligneous material. This extraction is ordi- 40 narilycarried out after separation of the insoluble or settled tar since this type of material, while insoluble in Water, is soluble in most ofthe extractants employed and would constitute an undesirable impurity in the acid extracts. The extraction of the acid portion of the pyroli'gneous liquor may be carried out in any one of several methods, of which the following are probably the most satisfactory. In one process the pyroligneous liquor is first de-methanolized and then The aqueous 40 .extractedwith a solvent forac'etic: acid. The aqueousresidue from this process contains, 501- uble tar. In. another method, after the pyrolig- "neous' liquor has' been de-methanolized, the re- .maining solution is subjected to evaporationpr distillation whereby acids and other volatile products are removedLfMost of the soluble tar; from. the pyroligneous-liquorjwill remain in the alternative procedure the insoluble .tarflmay be.

removed from green pyroligneous liquor which is then subjected to extraction. from the extraction, after aisubsequent concen- The residue as in the casting of magnesiumand similar readily oxidizable metals and their alloys. soluble tars contribute the desired binding char.-

from adhering particlesof sand. y

My new binding material may be used for Watermaking foundry cores in the usual manner by, mixing'the same withsand or other core-making 1 material and with water in correct proportions.

1 The resulting mixture can be formed into cores,

tration by evaporation or similar procedure, con- I Many ofthe processes for the recovery of 95.1;

molds, or portions of molds and baked in the.

' usual manner, forming hard cores or molds which can be handled and used in the usual way in T-making castings. The proportion of binder,

Water, and sand, orjitjs equivalent, will vary depending on the kind and fineness of the sand and-on the desired core characteristics. It may, on occasion, be desirable to incorporate in the evaporation or distillation of the methanol products'followed'b'yan azeotropic distillation .of water essary in' any of my work. -As an example of one withlcertain inert recoverable and ordinarily water-immisciblesolvents such as ethers, esters,

or, certain wood oil fractions. Such .a process tar satisfactory for use as a core binder. The

material,which distilled in the. evaporation step issubje'cted to azeotropic distillation; water, and ethyl ether'or thejlike passes oflf'as an azeotropic mixture while thefre'sidue from this distillation contains substantially dehydrated'acetic acid and a relatively small quantity of a soluble tar.

I g In all of'the usual .methods' employedfin thed recovery of what are ordinarily considered; to be r 3 valuable productseirom.pyroligneo'us liquor, a.

satisfactory water 's olub le' corefbinding material remains'in the aqueous residues from evaporation and/or distillation. ,Any such residues which, on

evaporation, with oriwithout previous separation of insoluble. or settled tars, :results' in a tarry residue from which. can be isolated a substantially water-soluble product of syrup y consistency, and

which exhibits a cohesiveeffect on core-making materials when mixed therewith and heated, is satisfactory for our purpose.

Although materials containing both soluble and insoluble tars may. be employed quite satisfactor'ily as core binders, IIprefer to employ. those residues. which are substantially free from the' insoluble substances; since' these latter materials 'do not contribute materially to the binding characteristics. of. the soluble tars, and further, be-

causethe insoluble materials are highly. colored, somewhat toxic substances, have an ofiensive odor, and are therefore unpleasant to handle. I

separation, neutralization, and/or extraction.

I haveemployed my newcore binding material inthe'preparation of sand cores for use in casting gray iron and'other ferrous metals as well core compositionsmall amounts ofother corei binding agents toaccomplish some special .pur-' pose, but I have not found this step to be nec- V isfactory for many. purposes, one part of watersoluble tar'having a specific gravity at 20/20 of 1.295, and. containing about .35 to per cent' water, was mixed with .40'par'ts, by volumeQof fine-lakersand and sufiioient water to give a for foundry use.' This core had a hard surface and was found to retain its strength'even when stored for several days in. a humid atmospherev prior-tense. From about 1.5 to about 5.0 per cent of'core binder, basedon the volume of sand,

is usually sufficient.

I have fo nd, in generalQthat less' baking is, requiredto produce a satisfactory core comprisingwate'r-solub'le.tarsthan with many .ofthe core-bindin'gagents heretofore employed. It has T also been observed that considerably lssqgas is:

evolved from the core composition during bak ing when waterj-solubletars are employed as the .2 binder'than when many other core-binding agents are emplo'yed. Good cores are produced when my new core-binding, material is employed with 7 clean sand,,but I have found that the binder'is especially. adapted for use in foundry sands con taining clay or silt. In either case, the use ,of-

Water-soluble tar as a binder 'resultsr'iot only in the production of good cores and molds after baking, but also produces a core or mold. compo:

sition having good wet'o'r. green strength prior to baking.

Other modes of applying the principle of my J invention may be employed instead of those ex,-

plained, change being made as regards the matef V rials employed, provided the ingredients stated by the following claim or the equivalent of such stated ingredients be employed. 7 I therefore particularly point .out and tinctly claim as my invention:

- As a core binder,.a viscous aqueous solution of the water-soluble tars obtained from pyroligneous j 'w; Go'os. T

dis- 

